A practicing architect should familiarize himself with such laws of the state, and such ordinances of the town or city in which he is employed as especially apply to his work. These laws and ordinances may concern him in many ways. It may be that such laws will require a license for the practice of an architect's profession; and they probably will impose building restrictions with which it is important for him to be familiar. He should know what, if any, privilege of inspection is vested in any persons by force of the law, and he should understand the requirements about building permits and other similar matters. It is sometimes provided that public contracts shall be awarded only after competition, and certain notice given, so that if the requirements are not complied with, such a contract will not be valid. In many places the building laws will be found to be collected and printed together; inquiry at a city hall for such a compilation is advisable. In other places it may be necessary to seek out the laws on these matters from general compilations,, It is a familiar maxim that ignorance of the law is no excuse for breach of it. Moreover it will be seen later that a person employing an architect has a right to rely on the architect's knowledge of building regulations; so that the hitter will be liable to his employer if through his ignorance the laws are infringed and the employer suffers. Service in the office of an architect of established practice has the advantage that many points of information of this sort, which it may be difficult to obtain elsewhere, become familiar to the student.